The present invention relates to a semiconductor device, a method of fabrication of the semiconductor device, a circuit board, together with an electronic instrument.
When a semiconductor device has been mounted on a substrate, it is important to relieve the stresses applied to the electrical connective portions of both components. These stresses are caused by the difference in the coefficients of thermal expansion of the semiconductor chip and the substrate. Since this is not possible to relieve such stresses sufficiently in the prior art, this leads to destruction of the external terminals (solder balls) of the semiconductor device and breakage of the wiring. In particular, this is expected to improve the reliability of wafer-level chip scale packaging (CSP), used to create packages in wafer units.